<?php
/**
 * reCAPTCHA symfony helper.
 * Mostly from http://recaptcha.net/plugins/php/
 * @author Massimiliano Arione
 *
 *
 * Copyright (c) 2007 reCAPTCHA -- http://recaptcha.net
 * AUTHORS:
 *   Mike Crawford
 *   Ben Maurer
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/**
 * The reCAPTCHA server URL's
 */
define('RECAPTCHA_API_SERVER', 'http://api.recaptcha.net');
define('RECAPTCHA_API_SECURE_SERVER', 'https://api-secure.recaptcha.net');
define('RECAPTCHA_VERIFY_SERVER', 'api-verify.recaptcha.net');

/**
 * Encodes the given data into a query string format
 * @param $data - array of string elements to be encoded
 * @return string - encoded request
 */
function _recaptcha_qsencode($data)
{
  $req = '';
  foreach ($data as $key => $value)
  {
    $req .= $key . '=' . urlencode(stripslashes($value)) . '&';
  }
  // Cut the last '&'
  $req = substr($req, 0, strlen($req) - 1);

  return $req;
}

/**
 * Submits an HTTP POST to a reCAPTCHA server
 * @param string $host
 * @param string $path
 * @param array $data
 * @param int port
 * @return array response
 */
function _recaptcha_http_post($host, $path, $data, $port = 80)
{

  $req = _recaptcha_qsencode($data);

  $http_request  = "POST $path HTTP/1.0\r\n";
  $http_request .= "Host: $host\r\n";
  $http_request .= "Content-Type: application/x-www-form-urlencoded;\r\n";
  $http_request .= "Content-Length: " . strlen($req) . "\r\n";
  $http_request .= "User-Agent: reCAPTCHA/PHP\r\n";
  $http_request .= "\r\n";
  $http_request .= $req;

  $response = '';
  if (false == $fs = @fsockopen($host, $port, $errno, $errstr, 10))
  {
    die('Could not open socket');
  }

  fwrite($fs, $http_request);

  while (!feof($fs))
  {
    $response .= fgets($fs, 1160); // One TCP-IP packet
  }
  fclose($fs);
  $response = explode("\r\n\r\n", $response, 2);

  return $response;
}

/**
 * Gets the challenge HTML (javascript and non-javascript version).
 * This is called from the browser, and the resulting reCAPTCHA HTML widget
 * is embedded within the HTML form it was called from.
 * @param string $pubkey A public key for reCAPTCHA
 * @param string $error The error given by reCAPTCHA (optional, default is null)
 * @param boolean $use_ssl Should the request be made over ssl? (optional, default is false)
 * @param boolean $strict  use XHTML strict (avoid iframe)
 * @return string - The HTML to be embedded in the user's form.
 */
function recaptcha_get_html($pubkey, $error = null, $use_ssl = false, $strict = false)
{
  if ($pubkey == null || $pubkey == '')
  {
    throw new Exception('To use reCAPTCHA you must get an API key from <a href="http://recaptcha.net/api/getkey">http://recaptcha.net/api/getkey</a>');
  }

  if ($use_ssl)
  {
    $server = RECAPTCHA_API_SECURE_SERVER;
  }
  else
  {
    $server = RECAPTCHA_API_SERVER;
  }

  $errorpart = '';
  if ($error)
  {
    $errorpart = '&amp;error=' . $error;
  }

  $html = '<script type="text/javascript" src="'. $server . '/challenge?k=' . $pubkey . $errorpart . '"></script><noscript>';

  if ($strict)
  {
    $html .= '<div><object style="width:500px;height:300px" type="text/html" data="'. $server . '/noscript?k=' . $pubkey . $errorpart . '"></object>' .
      '<textarea name="recaptcha_challenge_field" rows="3" cols="40"></textarea>' .
      '<input type="hidden" name="recaptcha_response_field" value="manual_challenge"/></div>' .
      '</noscript>';
  }
  else
  {
    $html .= '<iframe src="'. $server . '/noscript?k=' . $pubkey . $errorpart . '" height="300" width="500" frameborder="0"></iframe>' .
      '<textarea name="recaptcha_challenge_field" rows="3" cols="40"></textarea>' .
      '<input type="hidden" name="recaptcha_response_field" value="manual_challenge"/>' .
      '</noscript>';
  }

  return $html;
}


/**
 * A ReCaptchaResponse is returned from recaptcha_check_answer()
 */
class ReCaptchaResponse
{
  public $is_valid;
  public $error;
}


/**
  * Calls an HTTP POST function to verify if the user's guess was correct
  * @param string $privkey
  * @param string $remoteip
  * @param string $challenge
  * @param string $response
  * @param array $extra_params an array of extra variables to post to the server
  * @return ReCaptchaResponse
  */
function recaptcha_check_answer($privkey, $remoteip, $challenge, $response, $extra_params = array())
{
  if ($privkey == null || $privkey == '')
  {
    throw new Exception('To use reCAPTCHA you must get an API key from <a href="http://recaptcha.net/api/getkey">http://recaptcha.net/api/getkey</a>');
  }

  if ($remoteip == null || $remoteip == '')
  {
    throw new Exception('For security reasons, you must pass the remote ip to reCAPTCHA');
  }

  //discard spam submissions
  if ($challenge == null || strlen($challenge) == 0 || $response == null || strlen($response) == 0)
  {
    $recaptcha_response = new ReCaptchaResponse();
    $recaptcha_response->is_valid = false;
    $recaptcha_response->error = 'incorrect-captcha-sol';
    return $recaptcha_response;
  }

  $response = _recaptcha_http_post(RECAPTCHA_VERIFY_SERVER, "/verify", array(
    'privatekey' => $privkey,
    'remoteip'   => $remoteip,
    'challenge'  => $challenge,
    'response'   => $response
  ) + $extra_params);

  $answers = explode("\n", $response[1]);
  $recaptcha_response = new ReCaptchaResponse();

  if (trim($answers[0]) == 'true')
  {
    $recaptcha_response->is_valid = true;
  }
  else
  {
    $recaptcha_response->is_valid = false;
    $recaptcha_response->error = $answers[1];
  }

  return $recaptcha_response;
}

/**
 * gets a URL where the user can sign up for reCAPTCHA. If your application
 * has a configuration page where you enter a key, you should provide a link
 * using this function.
 * @param string $domain The domain where the page is hosted
 * @param string $appname The name of your application
 */
function recaptcha_get_signup_url($domain = null, $appname = null)
{
  return 'http://recaptcha.net/api/getkey?' .  _recaptcha_qsencode(array('domain' => $domain, 'app' => $appname));
}

function _recaptcha_aes_pad($val)
{
  $block_size = 16;
  $numpad = $block_size - (strlen($val) % $block_size);

  return str_pad($val, strlen($val) + $numpad, chr($numpad));
}

/* Mailhide related code */

function _recaptcha_aes_encrypt($val,$ky)
{
  if (!function_exists('mcrypt_encrypt'))
  {
    throw new Exception('To use reCAPTCHA Mailhide, you need to have the mcrypt php module installed.');
  }
  $mode = MCRYPT_MODE_CBC;
  $enc = MCRYPT_RIJNDAEL_128;
  $val = _recaptcha_aes_pad($val);

  return mcrypt_encrypt($enc, $ky, $val, $mode, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
}

function _recaptcha_mailhide_urlbase64($x)
{
  return strtr(base64_encode($x), '+/', '-_');
}

/* gets the reCAPTCHA Mailhide url for a given email, public key and private key */
function recaptcha_mailhide_url($pubkey, $privkey, $email)
{
  if ($pubkey == '' || $pubkey == null || $privkey == "" || $privkey == null)
  {
    throw new Exception('To use reCAPTCHA Mailhide, you have to sign up for a public and private key, ' .
                        'you can do so at <a href="http://mailhide.recaptcha.net/apikey">http://mailhide.recaptcha.net/apikey</a>');
  }

  $ky = pack('H*', $privkey);
  $cryptmail = _recaptcha_aes_encrypt($email, $ky);

  return 'http://mailhide.recaptcha.net/d?k=' . $pubkey . '&c=' . _recaptcha_mailhide_urlbase64 ($cryptmail);
}

/**
 * gets the parts of the email to expose to the user.
 * eg, given johndoe@example,com return ["john", "example.com"].
 * the email is then displayed as john...@example.com
 */
function _recaptcha_mailhide_email_parts($email)
{
  $arr = preg_split('/@/', $email);

  if (strlen($arr[0]) <= 4)
  {
    $arr[0] = substr($arr[0], 0, 1);
  }
  else if (strlen($arr[0]) <= 6)
  {
    $arr[0] = substr($arr[0], 0, 3);
  }
  else
  {
    $arr[0] = substr($arr[0], 0, 4);
  }

  return $arr;
}

/**
 * Gets html to display an email address given a public an private key.
 * to get a key, go to:
 *
 * http://mailhide.recaptcha.net/apikey
 */
function recaptcha_mailhide_html($pubkey, $privkey, $email)
{
  $emailparts = _recaptcha_mailhide_email_parts($email);
  $url = recaptcha_mailhide_url($pubkey, $privkey, $email);

  return htmlentities($emailparts[0]) . '<a href="' . htmlentities($url) .
    '" onclick="window.open("' . htmlentities($url) . '", "", "toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300"); return false;" title="Reveal this e-mail address">...</a>@' . htmlentities($emailparts[1]);
}
